Heat-transmitting tube



W. J. STILL HEAT TRANSMITTING TUBE June 11, 1929.

Original Filed Nov. 17, 1926 Patented June 11, 1929.

WILLIAM JOSEPH srrLL, or Lennon, ENGLAND.

HEAT-TRANSMITTING TUBE.

Original application. filed November 17, 1926, Serial No. 148,988, andinGreat Britain November 21, 1925. Divided and. this application filed,April 23, 1928. Serial No. 272,297.

This application is a division of my copcnding application filedNovember 17, 1926, and bearing Serial Number 148,988. a.

This invention relates to that class of heat transmitting elements whichare composed of a tube, upon which wire spirals are wound, such spiralsbeing in some cases secured to the tube by soldering or the like, and bya. binding wire passed through the spiral.

It has been established that a great increase in the rate of heattransmission between fluids o f diiierent temperature within and withouta tube is effected if the velocities of flow over the surfaces areincreased.

For example assume a tube containing hot water over which air at a lowertemperature is passed, the rate of heat transmission from the water tothe air will increase if the velocity of the air over the tube surfaceis increased, or conversely consider a tube containing cold water andhot gases are passed over the surface of the tube, the heat will betransmitted to the water at a higher rate it the velocity of the hotgases over the surface of the tube is increased. Moreover it has beenestablished that the use of tubes of small diameter. is beneficial andthat there is an appreciable increase in the heat transmissionelliciency if the flow of air or gas is across tubes set in zig-zagfashion instead of through them. It thus follows that heat flow is notconstant for a given air flow but that the disposition of the surfacesmay alter it materially.

The real problem is to provide means by which the fluid passing over thetube is constantly subdivided and caused to come into contact with freshsurfaces and the invention may be said to consist broadly of a heattransmission element consisting of a tube having radiating from it theparallel sides of a hollow ribbon of spiral wire secured thereon inheatconducting relation with the tube and so disposed as to divide thefluidfor instance, airpassing over it into thin streams so as to bringthe particles into intimate contact with a heat conducting surface. I

The specific form the invention takes in practice is a metal tube ofsuitable diameter havingspirally wound upon it a ribbon'of wire woundinto the form of a hollow flat sided strip which is applied edgewise tothe tube as will hereafter more clearly appear.

The commercial manufacture of the wire ribbon and the application of itto the tube in heat conducting relation-involves the use of a speciallydesigned machine as described inmy specification of Serial No. 148,988.

The invention will be more clearly understood on reference to theaccompanying drawings and detailed description.

Figure 1 is an elevational full size view of a piece of a commercialtube element manufactured in accordance with and embodying theadvantages of my invention.

Figure 2 is an end view thereof.

Figure 3 is a view illustrating a section on the line 6--6 of Figure 2.

Figure 4 is a longitudinal section of a portion of the finished tube,and Figure 5 is a side and an end elevation of a portion of the hollowflat-sided or ribbon coil.

It is not practical to cast or otherwise form a tube with a multiplicityof rods but precisely the same effect is obtained by constructing thetube element in the manner illustrated in Figs. 1 to 5 which will now bereferred to. In these figures the tube 1 is an ordinary tube as beforebut the radiating elements are constituted by winding spirally on thetube a. hollow ribbon 6 made of copper wire or other heat conductingmaterial this ribbon being flat on its sides so as to be initially inthe form of a ribbon and not a spiral wire tube of circular sectionwhich has been proved in the past to be inefficient. Thepleferred formof a piece of this ribbon is illustrated in Fig. 5. The hollow flatsided spiral 6 may be bound on the tube 1 by means of one or morebinding wires 7 arranged within it, the free ends of each binding wire 7being positively connected to the tube 1 by spot welding or otherwise.The soldering of thespiral 6 on the tube may be effected by winding awire of solder upon the tube side by "side with the spiral 6 andsubjecting the tube to a temperature above the melting point of thesolder. The edge of the spiral which abuts upon the surface of the tubemay be milled prior to the winding operation, as shown at- 6' Fig. 5.

, \Vhat I claim and desire to secure by Letters Patent is 1. A heattransmitting element consisting of a tube having spirally wound thereonand secured edgewise a hollow ribbon of spirally wound wire.

2. A heat transmitting element compris- IOU ing a :tubf a. hollow ribbonof spirally wound wire, the hollow'ribbon bein wound edgewise spirallyround the tube undsecured thereto at its contacting edge:

3. A heat transmitting element, comprising a tube, a hollow ribbon ofspirally wouncLwire, and at binding wire, the hollow ribbon beingwound'edgewise-spirally round' the tube and the binding wire ,arrangedwithin the hollow ribbon and pressing and holding the innernarrow]edgelhereof in eontuctwith the tube.

4. A heat transmitting element comprising utube, and a hollow ribbon ofspirally wound wire,the hollow ribbon being'wound edgewise spirallyround the tube and soldered thereto at its contacting edge.

5. A heat transmitting elementcomprising a tube, 'a hollow ribbon ofspirally wound wire, and-a binding wire, the hollow ribbon being woundedge'wi'se spirally-round the tube and the binding wire arranged withinthe hollow ribbon and pressing and holding the inner 'nirrrow edgethereof in contact with the tube the free ends of the binding wire beingwelded tothe tube. In witness whereof I'afiix n'|y"signuture.

- H WILLIAM JosEm- STILL.

